You just had an operation to get rid of your blindness, you go out an turn into a rat-possum-hare you go on an?

If you can talk to one other species, like possum to pelican, why not all other species, including human? That's what I think makes Rita Mae Brown's books so annoying: all birds and all mammals except humans can all talk to each other, with no explanation why humans don't hear other mammals and why no one talks to amphibians or insects. I'd say everyone to talks everyone or else species by species.